I should probably clarify now, before I end up confusing things: The 'cube' inside the Golett is, in fact, the famed Shadow Bottle that the pokemon on the tower alerted Ankara and Lily about (though the don't know about it, and probably won't).
Also, Krjl unlocked a couple new abilities with the Aura Band. His aura sense is stronger, and he now is able to learn TM moves that a Lucario's can learn that he normally wouldn't be able to, like Swords Dance and Flash Cannon.
"Which is more evil: Kidnapping a child to use as a tool for world domination, or using your blood child as a tool for world domination?"-Tyranidomega